| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | a long period [prep] [adj] | 29 |
|
| 2 | a long period [prep] [adj] | 28 |
|
| 3 | a long period of [adj] | 26 |
|
| 4 | a longer period [prep] [adj] | 5 |
|
